Electrostatic coating processes rely on a charge differential between an article to be coated and what is used to coat that article. In such processes, the article is typically grounded whereas the coating to be applied is endowed with a charge. When the article and coating are then brought into contact with one another, the result is that the coating adheres to the article. It is estimated that more than 10,000 facilities for accomplishing this exist in the U.S. alone.
Most such coating procedures and facilities employ a variety of steps, i.e., a cleaning step, a drying step, a coating step, and a heating step wherein the adhered coating is cured to afford a more desirable and permanent coat. These steps usually take place sequentially using batch operations commonly employed in the art, or else in specialized stations connected by a continuous conveyor line.
Conveyor lines can be of varying length depending on the facility. Articles to be coated are hung from these lines via spaced electroconductive racks or hangers that serve to ground articles attached thereto. Racks and hangers are popular that have the capacity to hang multiple articles. This is accomplished by multiple hooks, usually spot welded at set distances from one another on the same rack. Such rack and hook configurations vary widely in shape, size, and configuration to support different types and sizes of articles.
Once attached, the hangers or racks bearing grounded articles are conveyed through a coating station followed by a curing station. Once coating and curing are finished, the coated objects are removed and the process begins anew.
The hangers and racks of such systems, being expensive, are typically re-used. After passing through the coating station a number of times, that portion or portions of the hanger which contact the article gradually becomes fouled by the coating. The net effect is interference with grounding capacity, with consequent poor coating of the article, and an eventual possibility for spark or fire. This necessitates periodic replacing or cleaning of the racks or hangers, i.e., hooks, which is both time-consuming and expensive.
In the case of cleaning for re-use, conventional cleaning methods include chemical stripping, molten bath stripping, burning, and mechanical stripping, i.e., sandblasting, hammering, and filing. These processes reduce the useful life and capacity of racks, hangers, and hooks by compromising their structural integrity over time. For example, it is the Applicant's experience that hooks break off fairly regularly, thereby lessening the capacity and desirability of continuing with that rack. This necessitates, at considerable expense, either repair of the old rack or replacement with a new rack.
The art has thus far failed to provide a cost-effective alternative.